Mobile terminal devices, also known as mobile communication devices, refer to computer equipments that can be used when they are moving. For example, mobile phones, notebooks, tablet computers, POS devices, and vehicle mounted on-board computers all belong to mobile terminals. Along with the development of internet technology and integrated circuit technology, mobile terminal devices are progressing to handle complex information processing.
Usually, mobile terminal devices can communicate with external devices through interfaces such as WiFi, USB, Audio Jack, or Bluetooth. However, when there is no such interface, communication between a mobile terminal device and an external device is a problem.